In the past, transfer dopping, as the transfer process is called, has been accomplished in a number of ways.
One such way simply involves adhesively cementing or mounting the gemstone on the dop with wax. Heated wax is placed on the end of the dop, the gemstone is contacted with the waxed dop while the wax is still hot, and the gemstone is securely adhered thereto when the wax cools. The dop is subsequently placed in the indexing head and the desired facets cut on the free end of the gemstone. The dop is thereafter removed from the indexing head, and the finished end of the gemstone is secured to a second dop. The latter dop is remounted loosely in the indexing head, brought into contact with the lap and visually rotatably adjusted until a base of one of the previously cut facets is substantially parallel to the surface of the lap. Thus oriented, the dop is then secured, and the cutting of the unfinished end of the gemstone undertaken.
While visual positioning is simple, it has the inherent drawback of depending on the cutter's visual acuity and skill, and it oftentimes produces stones with facets slightly misaligned at the girdle, with the undesirable consequences previously described.
Another way which has been suggested is that described in U.S. Pat. No. 2,724,220, wherein the dopsticks employed have a small locating pin projecting at right angles from the dops. When one end of a gemstone mounted on a dop has been faceted, it is placed in a bracket with the pin in contact with a bracket surface. A second dop whose projecting pin is also in contact with the common surface is then brought into contact with the free end of the gemstone; the second dop is attached thereto, and the connection of the gemstone with the first dop is severed. The transferred gemstone thus maintains its relativity with respect to the pin of the dop on which it is mounted at any given point in the process. The pin also serves to engage the indexing head, determining the orientation of the gemstone to the head, and therefore to the lap.
While the method has distinct advantages over the visual system described, it does have a number of deficiencies. Its usefulness is for instance, limited to a specific mechanical faceting device, that is, one adapted to receive a dop positioning pin of the type described. While the mechanical faceting device taught in the Patent obviously is so adapted, it requires different holders to receive the special dop in order to cut particular ones of the different facet arrangements possible. A "brilliant" cut, for example, necessitates a different dop holder than in an instance where a different shaped gemstone, or one with different facet spacing is desired. Furthermore, as will be appreciated, specialized dops are required, which are not commonly available.
Now, however, a method has been found which permits transfer dopping to be accomplished involving the transfer of a gemstone from one dop stick to another, while maintaining precise alignment of the gemstone relative to the dop in its mounted position in the indexing head of a mechanical faceting device.
The method of the invention is easily and quickly accomplished, even by unskilled cutters, and it uses dopsticks commonly employed in faceting gemstones by any of a number of methods.
Dop transfer, as carried out by the invention herein described, is useful in a variety of mechanical faceting devices, rather than being restricted to a specific mechanical faceting device.
By means of the invention, the transfer is accomplished through use of a dop transfer device or "jig" of a simple design that lends itself to retrofitting many existing transfer devices.